hennebique



No. 6||,907. Patented 0ct..4, I898.

F. HENNEBIQUE. CONSTBUCTIUN OF JDIS TS, GIRDER S, AND THE LIKE.

(Application file; Dec. 29, 1897.)

(No llodeh) NITED STATES AFTENT FFI FRANQOIS IIENNEBIQUE, OF PARIS,FRANCE.

CONSTRUCTION OF JOISTS, GIRDERS, AND THE LIKE.

SPECIFICATION forming part of Letters Patent No. 611,907, dated October4, 1898.

Application filed December 29, 1897. Serial No. 664,329. (No model.)

T at whom it may concern.-

Be it known that I, FRANooIs' HENNEBIQUE, a citizen of the Republic ofFrance, residing at Paris, France, have invented certain new and usefulImprovements in the Construction of J oists, Girders, and the Like ofCement Strengthened with lron, of which the following is aspecification.

The use of strengthened beton in buildings has within recent yearsgreatly developed. It has been thoughtpossible bymixing beton and iron'or steel to replace the purely metallic elements of buildingconstruction by parts equally incornbustible but lighter and more simplyand rapidly made. In any case the mixture of cement or hydraulic lime,which resists perfectly compression with iron or steel, which moreparticularly resists tension and flexion, has not hitherto been capableof being carried outin a judicious and rational manner.

By arranging at useful points in a mass of beton of suitable formlongitudinal bars of iron of a given shape in order to constitute thetension-chord, by distributing them in the mass in a judicious manner inorder that the whole mass of iron and beton may have at every point ofthe piece formed the desired resistance to fiexion and tension, and byfurther connecting the longitudinal bars by brace-pieces or stirrups ofsuitable form I have succeeded in producing the practical joists,girders, and the like which form the object of my present invention.

The invention is illustrated in the accompanyingdrawings,in WhichIhaveshown diagrammatically in Figure 1 a practical continuous joist orgirder of beton strengthened withiron arranged according to theseprinciples. Fig. 2 is a detail perspective view of one of thestirrup-pieces. Fig. 3 is a section on line 8 t of Fig. 1. Fig. 4 is asectional perspective on line as y of Fig. 3, the longitudinal half ofthe girder being supposed to be removed. Fig. 5 is a detail illustratingthe construction at the point of passing an intermediate support.

This joist incased or built in at one of its ends A is placed on aseries of intermediate supports 0. The characteristic of the metalliccore or strengthening is the addition to longitudinal bars 1, arrangedparallel to the lower side of the joist, of inwardlybent bars ble theresistance of the latter to tension.

They'are carried by the same supports 0r stirrups 3, and' these latterthus connect the chord of tension formed by the bars with the chord ofcompression formed by the beton. One of these stirrup-pieces is shown inperspective in Fig. 2. It is formed of a band of sheet-iron of U shapehaving straight arms, terminated by a little hook, which facilitatestheir fixing in the beton. These straight stirrup-pieces play in thejoist of strengthened beton the part which the suspension-rods play inthe trussing of metallic girders.

As in the extreme parts of the girder the tension action increases inproportion as the Wall A and the support 0 are approached, I raise thebar 2. The inclined arms 2 of this bar are connected with the horizontalbar 1 by stirrup-pieces 3, approached more and more closely together. Ithus form a triangle of resistance, the apex of which is at the point ofdivergence of the bars at 2. This triangle, in consequence of thestirrup-pieces 3 being progressively placed nearer one another and ofthe growing mass of beton which it incloses between the bars 1 and 2,offers a proportionate increasing resistance to the ten sion action.Each bar 2 is inclined upwardly at 2, runs horizontally, as shown at 2",and is extended beyond the incline of the adjacent bar, as shown at 2.

At the point where the continuous girder passes on to an intermediatesupport 0, I prolong the bar 2 to 2 in the adjoining compartment or bay,which is thereby strengthened, and in order to insure that the reactionof the beton of this prolongation shall not raise the latter I crown itwith reversed stirrups Ct, which maintain the bar perfectly firm.

Fig. 5 shows in detail the passing over an intermediate support 0. Thecrossing of the arms 2" consolidates the girder in a practical manner onthe support 0, where the bending strain is greatest. It will be seen,therefore, that owing to the addition of a single bar 2, the arms 2 2 ofwhich are suitablyinclined, connected, and arranged in the beton, and,further, owing to the rational distribution of the straight stirrups 3,it is possible to construct girders resistant in all their parts in aperfect manner to the effects of tension, the effects of compression,the breaking effects, and the bending effects, while reducing to aminimum the quantity of iron employed and suppressing or dispensing withiron in the part under compression, thereby avoiding between the irons 1and 2 any crossfastening by inclined stirrups or by Wire lattice-work.

It is needless to state that the principles hereinhefore described maybe applied to the manufacture of any suitable girders or joists forceilings or floors and, in fact, to any constructions formed of betonstrengthened with metal, which, as regards the strains which they willsupport, may be likened to girders placed on supports or incased inmasonry. It is also understood that according to the dimensions of thegirder, the transverse section of which is not necessarily rectangular,the number or bars 1 and 2 placed in the same vertical plane may vary.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is- 1. In the construction of joists, girders and the likeof cement strengthened with iron or the like, the inwardly-bent bars 22'2 2 of which the central branch 2 is horizontal and arranged in theplane of the bar 1 which forms the chord of tension of the girderand ofwhich the arms 2 are always raised in the same verical plane and in thedirection of the point where they are fitted into the wall A or on thesupports C, in order to obtain a better resistance to the increasingbreaking strain, while the branch 2" is extended into the next span,substantially as described.

2. In the construction of joists, girders, or the like of the kinddescribed, the straight stirrup-pieces 3 of hoop-iron in a U form forconmeeting the bars 1 and the inwardly-bent bars 2 2 2" 2, the saidstirrup-pieces being distributed in the girder, substantially ashereinbefore described.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

FRANQOIS HENNEBIQUE. lVitnesses:

EMILY BERT, SNOTE MORTIER REL

